Voice coil motor

ABSTRACT

An exemplary embodiment of the present invention a rotor including a lens and formed with a first driving unit, a stator formed with a second driving unit driving the rotor in response to electromagnetic interaction with the first driving unit, and a base on which the stator is fixed, wherein the rotor is brought into contact with the base, in a case the lens is in a UP posture, and the rotor is distanced from the base, in a case the lens is in a DOWN posture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/142,951, filed Apr. 29, 2016; which is a continuation of U.S.application Ser. No. 14/398,359, filed Oct. 31, 2014, now U.S. Pat. No.9,341,810, issued May 17, 2016; which is the U.S. national stageapplication of International Patent Application No. PCT/KR2013/002902,filed Apr. 8, 2013; which claims priority to Korean Application Nos.10-2012-0049186, filed May 9, 2012; 10-2012-0091168, filed Aug. 21,2012; and 10-2012-0091169, filed Aug. 21, 2012; which are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The teachings in accordance with exemplary and non-limiting embodimentsof this disclosure relate generally to a voice coil motor.

BACKGROUND ART

Recently, a mobile phone or a smart phone mounted with a camera modulecapable of storing an object in a digital still image or a video imagehas been developed. A conventional camera module includes a lens and animage sensor module configured to convert light having passed the lensto a digital image.

However, the conventional camera module suffers from disadvantages forlack of an auto focus function automatically adjusting a gap between alens and an image sensor module, resulting in difficulty in obtaining ahigh quality digital image and resultantly leading to an image qualitydegradation caused by handshake generated by user handshake.

DISCLOSURE Technical Problem

The present disclosure is to provide a VCM (Voice Coil Motor) configuredto simultaneously perform focusing operation and handshake compensationfunctions while a lens horizontally moves relative to an image sensor.The present disclosure is also to provide a VCM configured to reduce aconsumption current by variably changing a posture of a rotor inresponse to a lens posture.

Technical Solution

In one exemplary embodiment of the present disclosure, there is provideda camera module, the camera module comprising:

a rotor including a lens and formed with a first driving unit;

a stator formed with a second driving unit driving the rotor in responseto electromagnetic interaction with the first driving unit; and a baseon which the stator is fixed, wherein the rotor is brought into contactwith the base, in a case the lens is in a UP posture, and the rotor isdistanced from the base, in a case the lens is in a DOWN posture.

In another exemplary embodiment of the present disclosure, there isprovided a VCM (Voice Coil Motor), the VCM comprising:

a rotor including a first driving unit arranged at a periphery of abobbin fixing a lens;

a stator including a second driving unit opposite to the first drivingunit and a housing fixing the second driving unit;

an elastic member coupled at one side to the rotor and coupled at theother side to the stator;

a base supporting the stator and having an opening exposing the lens;and

a case covering the housing and being coupled to the base, wherein aninterference prevention unit is formed at any one of the case and thehousing to inhibit a part of the elastic member from interfering withthe case or the housing, in a case the rotor ascends or descendsrelative to the stator.

Advantageous Effects

An exemplary embodiment of the present invention has an advantageouseffect in that current consumption can be reduced and a camera modulecan be driven under an optimum condition by detecting a posture of a VCMor a lens and controlling the VCM using a posture data.

Another advantageous effect is that an actuator is removed of mechanicaloffset to reduce current consumption, to enhance a design freedom ofelectromagnetic force, to solve a defocusing problem by applying acurrent to an opposite direction even if there is generated a change inspring, and to improve a yield of a camera module by dispensing with aninitial focusing.

Still another advantageous effect is that a VCM is inhibited fromgenerating a driving fault during a focusing operation by maintaining arotor to be in a state of being distanced from a base in a case nodriving signal is applied, driving the rotor to both directions offacing a base or distancing from the base through application of thedriving signal, and by inhibiting an elastic member coupled to the rotorfrom interfering with a case covering the rotor, in a case the rotor isparticularly driven to both directions.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a camera module including a VCMaccording to an exemplary embodiment of the present invention.

FIG. 2 is a conceptual cross-sectional view illustrating an UP postureof a lens of a VCM according to an exemplary embodiment of the presentinvention.

FIG. 3 is a conceptual cross-sectional view illustrating a SIDE postureof a lens of a VCM according to an exemplary embodiment of the presentinvention.

FIG. 4 is a conceptual cross-sectional view illustrating a DOWN postureof a lens of a VCM according to an exemplary embodiment of the presentinvention.

FIG. 5 is a graph illustrating a current-distance characteristic basedon a posture of a VCM according to an exemplary embodiment of thepresent invention.

FIG. 6 is conceptual diagram illustrating a VCM according to anexemplary embodiment of the present invention.

FIG. 7 is an exploded perspective view illustrating the VCM of FIG. 6.

FIG. 8 is a perspective view illustrating a housing of FIG. 6.

FIG. 9 is a cross-sectional view illustrating the housing of FIG. 6.

FIG. 10 is a cross-sectional view illustrating the housing according toanother exemplary embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a bobbin of FIG. 6 in astopped state.

FIG. 12 is a cross-sectional view illustrating a state of the bobbin ofFIG. 6 lifted to a direction distancing from a base.

FIG. 13 is a cross-sectional view illustrating a state of the bobbin ofFIG. 1 descended to a direction approaching the base.

FIG. 14 is an exploded perspective view illustrating the VCM of FIG. 6.

FIG. 15 is a perspective view illustrating a VCM removed of a covermember and an elastic member of FIG. 6.

FIG. 16 is a plan illustrating parts of a case, an interferenceprevention unit and an elastic member of FIG. 6.

FIG. 17 is a cross-sectional view illustrating a case, an interferenceprevention unit, an elastic member and a bobbin.

FIG. 18 is a cross-sectional view illustrating a state of the bobbin ofFIG. 17 being lifted from the base.

FIG. 19 is a cross-sectional view illustrating a state of the bobbin ofFIG. 17 being descended toward the base.

DETAILED DESCRIPTION First Exemplary Embodiment

FIG. 1 is a block diagram illustrating a camera module including a VCMaccording to an exemplary embodiment of the present invention.

Referring to FIG. 1, the camera module according to the exemplaryembodiment of the present invention includes a VCM (Voice Coil Motor,100), a posture detection sensor (200), an auto focus algorithm (300),an ISP (Image Signal Processor. 400), an image sensor (500) and acontroller (600), where the VCM (100) includes a rotor including a lens,and performs an auto focusing operation of the VCM (100) of the cameramodule in response to an electromagnetic force.

Furthermore, the posture detection sensor (200) outputs a posture databy determining a posture of the VCM (100) or a lens, and the ISP (400)generates a driving signal for driving the VCM using an optimum focusvalue of the lens calculated by the auto focus algorithm (300), whereinthe optimum focus value is generated by a posture data corresponding toa posture of the VCM outputted from the posture detection sensor (200).

At this time, the posture detection sensor (200) may include a gyrosensor detecting a direction of gravity. The auto focus algorithm (300)outputs a detection signal by detecting an optimum focus value of theVCM based on a distance from an object in order to accurately realizethe auto focusing and to realize a fast auto focusing response time. Theauto focus algorithm (300) may be used in the form of an algorithminside the image signal processor (400), or may be used by beingembedded in a chip separate from the image sensor processor (400).

Hence, the posture detection sensor (200) senses three kinds of posturesof the VCM or the lens, as described later, where, although the posturedetection sensor (200) can sense three or more kinds of postures of theVCM (100) or the lens, an exemplary embodiment of the present disclosuredescribes that the posture detection sensor (200) senses three kinds ofpostures of the VCM (100) or the lens including UP, SIDE and DOWNpostures, for explanation convenience.

Furthermore, the image sensor (500) converts light having passed thelens to a digital signal, and the controller (600) controls the VCM(100), the posture detection sensor (200), the image signal processor(400) and the image sensor (500). The controller (600) is connected tothe VCM (100), the posture detection sensor (200), the image signalprocessor (400) and the image sensor (500) via a data bus and/or acontrol bus.

Thus, an exemplary embodiment of the present disclosure is advantageousin that a posture of the VCM or a lens is detected, the VCM iscontrolled using the posture of the VCM or the lens to reduce currentconsumption, and the VCM (100) of the camera module is driven on anoptimum base.

FIG. 2 is a conceptual cross-sectional view illustrating an UP postureof a lens of a VCM according to an exemplary embodiment of the presentinvention, FIG. 3 is a conceptual cross-sectional view illustrating aSIDE posture of a lens of a VCM according to an exemplary embodiment ofthe present invention, and FIG. 4 is a conceptual cross-sectional viewillustrating a DOWN posture of a lens of a VCM according to an exemplaryembodiment of the present invention.

FIG. 2 is a conceptual cross-sectional view illustrating an UP postureof a lens of a VCM at the camera module according to an exemplaryembodiment of the present invention, where the “UP posture” may bedefined in such a manner that an optical axis of a lens (135) of a rotor(130) at a VCM is formed to a direction vertical to a ground, and a base(110) is in a position facing the ground.

FIG. 3 is a conceptual cross-sectional view illustrating a SIDE postureof a lens of a VCM according to an exemplary embodiment of the presentinvention, where the “SIDE posture” may be defined in such a manner thatan optical axis of a lens (135) of a rotor (130) at a VCM is formed to adirection parallel with a ground, and a base (110) is in a positionperpendicular to the ground.

FIG. 4 is a conceptual cross-sectional view illustrating a DOWN postureof a lens of a VCM according to an exemplary embodiment of the presentinvention, where the “DOWN posture” may be defined in such a manner thatan optical axis of a lens (135) of a rotor (130) of a VCM (100) isformed to a direction perpendicular to a ground, and a cover (150) is ina position facing the ground.

At this time, the VCM according to an exemplary embodiment of thepresent invention includes a lens (135), a rotor (130) formed with afirst driving unit (138), a stator (120) formed with a second drivingunit driving the rotor (130) in response to electromagnetic interactionwith the first driving unit (138), and a base (110) on which the stator(120) is fixed, where the rotor (130) is brought into contact with thebase (110), in a case the lens (135) is in an UP posture, and the rotor(130) is distanced from the base (110), in a case the lens (135) is in aDOWN posture.

Furthermore, some offsets may exist, in a case the lens (135) is in anUP posture or in a SIDE posture, and the offset may cease to existbecause of droop caused by self-weight of the rotor (135) to agravitational direction, in a case the lens (135) is in a DOWN posture.At this time, the rotor (130), the stator (120) and the base (110) maybe parts of the VCM (100).

Referring to FIG. 2, the VCM (100) performs the auto focus function bydriving the lens (135). By way of example, the lens (135) mounted on theVCM (100) is moved to a direction ascending from the base (110), duringwhich time the auto focus operation is performed between the lens (135)and the image sensor (300).

The VCM (100) may include a base (110), a stator (120), a rotor (130),an elastic member (140) and a cover (150). Furthermore, the base (110)takes a shape of a plate centrally formed with an opening for passinglight, and serves as a lower stopper of the rotor (130). The base (110)may be formed at a rear surface or a direction to the rear surface withthe image sensor (500), where the image sensor (500) converts the lightfocused by the light of the rotor (130) to a digital image or a videoimage.

Furthermore, the stator (120) is fixed on the base (110). At this time,the first driving unit (138) may be a magnet and the second driving unit(125) may be a wound coil. Alternatively, the first driving unit (138)may be a wound coil and the second driving unit (125) may be a magnet.

Furthermore, the stator (120) may be formed therein with anaccommodation space in which the rotor (130) may be positioned. Inaddition, the elastic member (140) may be fixed at one side to the rotor(130), and fixed at the other side opposite to the one side to thestator (120), where the elastic member (140) may elastically support therotor (130).

In the exemplary embodiment of the present disclosure, the elasticmember (140) may include a first elastic member (143) formed at a bottomperipheral surface of the rotor (130) and a second elastic member (146)formed at an upper peripheral surface of the rotor (130). In a case thelens of FIG. 2 is at an UP posture facing an upper side direction, theelastic member (140) contacts the rotor (130), in a case noelectromagnetic force is applied to the second driving unit of thestator (120) and the first driving unit (138) of the rotor (130). Thatis, the elastic member (140) is such that the rotor (130) contacts theupper surface of the base (110) by the weight of the rotor (130), in acase no electromagnetic force is applied to the second driving unit ofthe stator (120) and the first driving unit (138) of the rotor (130).

At this time, the VCM (100) recognizes that an approximately 0.03 mm ofoffset exists between the rotor (130) and the upper surface of the base(110). Hence, while the lens of FIG. 2 is an UP posture positioned at anupper side, the VCM (100) according to an exemplary embodiment of thepresent disclosure needs a greater electromagnetic force than theelasticity of the elastic member (140) and the self-weight of the rotor(130) in order to lift the rotor (130) from the base (100). In addition,the cover (150) is fixed to the base (110) to wrap the stator (120) andthe rotor (130). The cover (150) functions as an upper stopper to stopthe rotor (130).

Meanwhile, the present disclosure may be so configured as to allow therotor (130) to contact the base (110) while the lens (135) is at the UPposture, and the rotor (130) to be distanced from the base (110) whilethe lens (135) is at a SIDE posture or a DOWN posture.

Furthermore, the VCM (100) may be applicable by an actuator driving alens, an actuator driven by piezoelectric power, or a MEMS (MicroElectro Mechanical System) actuator driven by electrostatic capacitymethod. That is, an actuator driving a lens of a camera module may beone of a VCM actuator, an actuator driven by piezoelectric power, and aMEMS (Micro Electro Mechanical System) actuator driven by electrostaticcapacity method.

At this time, the VCM (100) may include an actuator (130) including alens (135) and an actuator driving the rotor (130). In a case the lens(135) is at an UP posture or a SIDE posture, the actuator (130) may bebrought into contact with the base (110) functioning as a stopper of therotor (130), in a case the lens (135) is at a DOWN posture, the actuator(130) may be distanced from the base (110), or in a case the lens (135)is at an UP posture, the actuator (130) may be brought into contact withthe base (110), or in a case the lens (135) is at a SIDE posture or at aDOWN posture, the actuator (130) may be distanced from the base (110).

Thus, the present disclosure is advantageous in that the actuator isremoved of mechanical offset to reduce current consumption, a designfreedom of electromagnetic force is enhanced to solve a defocus problemeven if a current is applied to a reverse direction due to change inspring, and an initial focusing is dispensed with to improve a yield ofVCM of a camera module.

FIG. 5 is a graph illustrating a current-distance characteristic basedon a posture of a VCM according to an exemplary embodiment of thepresent invention.

Referring to FIG. 5, the rotor must be in contact with the base at theUP posture of the VCM of the camera module, and the driving unit may beapplied with a current greater than a reference level, because anelectromagnetic force greater than the elasticity of the elastic memberand the self-weight of the rotor is required to lift or float the rotorfrom the base.

Hence, the UP posture of the VCM of the camera module in FIG. 5 can have‘A’ auto focus search section. Thus, the rotor is not driven by acurrent less than a reference current [mA] in FIG. 5, and therefore acurrent section with a current less than the reference current [mA] maybe defined as a non-driving section where the rotor is not operated, andno auto focus operation is realized at the non-driving section where therotor is not operated.

Furthermore, the rotor is driven by a current greater than the referencecurrent [mA] where the electromagnetic force driving the rotor becomesgreater than the elasticity of the elastic member and the self-weight ofthe rotor. At this time, a current section with a current greater thanthe reference current [mA] may be defined as a section where the rotoris driven, where the rotor is operated, and the auto focus operation isrealized at last at a driving section where the rotor is operated.

Furthermore, although the rotor is in contact with the base at the SIDEposture of the VCM of the camera module, the rotor is not driven butstarts to be driven at the moment a current is applied to the rotor,because the elasticity of the elastic member and the self-weight of therotor was not considered for lifting or floating the rotor from thebase. Hence, the SIDE posture of the VCM of the camera module can have‘B’ auto focus search section of FIG. 5. At this time, the VCM arrangedat the SIDE posture can be driven by a current less than a current atthe VCM at the UP posture. That is, a start current for driving therotor at the SIDE posture is smaller than that for driving the rotor atthe UP posture.

At this time, a start current at the SIDE posture of the VCM of thecamera module may be in the range of 0 mA˜10 mA, and a posturedifference between the UP posture and the SIDE posture may beapproximately 30˜50 μm. At the same time, the rotor is distanced fromthe base in a case the VCM of the camera module is at the DOWN posture,and has a ‘C’ auto focus search section in FIG. 5, whereby the rotor maybe reversely driven at the DOWN posture of the VCM of the camera module.

Second Exemplary Embodiment

Now, a second exemplary embodiment of the present disclosure will bedescribed, where different reference numerals will be provided to thesame configuration as that of the first exemplary embodiment of thepresent disclosure in order to distinguish the second exemplaryembodiment from the first exemplary embodiment.

FIG. 6 is conceptual diagram illustrating a VCM according to anexemplary embodiment of the present invention.

Referring to FIG. 6, a VCM (1000) performs an auto focus function alongwith a handshake compensation function.

The auto focus function is a function to drive a rotor (1100) from astator (1200), and in order to perform the auto focus function, therotor (1100) and a base (1300) mounted with a lens for performing theauto focus function are distanced from each other in a case the rotor(1100) and/or the stator (1200) are not applied with a driving signal.

The rotor (1100) is driven to a first direction distancing from the base(1300) as the driving signal lifting or floating the rotor (1100)floated from the base (1300) to perform a particular focus function(macro focus). The rotor (1100) is driven to a second direction nearingto the base (1300) to perform a particular focus function (infinityfocus), in a case a driving signal for descending the rotor (1100)floated from the base (1300).

In a case mutually different driving signals are applied to the rotor(1100) floated from the base (1300), current consumption is reduced byreduction of current amount, whereby a low power consumptioncharacteristic can be realized, and a driving distance of the rotor(1100) is reduced to further reduce a time consumed for auto focusingoperation of the rotor (1100).

Hereinafter, a VCM (1800) having an auto focus function and handshakecompensation function by bidirectional driving thus described will beexplained in detail.

FIG. 7 is an exploded perspective view illustrating the VCM of FIG. 6.

Referring to FIGS. 6 and 7, the VCM (1800) includes a rotor (1100), astator (1200), an elastic member (1250), a base (1300) and a case(1400).

The rotor (1100) includes a bobbin (1110) and a base (1300). The rotor(1100) performs an auto focusing function by being vertically moved atan upper surface of the base in response to interaction with the stator(1200, described later) and performs a handshake compensation functionby being tilted at the upper surface of the base (1300).

The bobbin (1110) takes a cylindrical shape, for example, and is formedat an inner periphery with a female screw unit for being coupled with alens (1130). The bobbin (1110) is formed with a coupling lug (1112) forbeing coupled to an elastic member (1250, described later). The bobbin(1110) is alternatively formed at an outer periphery with a curvedsection and a straight section. The bobbin (1110) is formed at the outerperiphery with four (4) straight sections and four (4) curved sections.

Grooves concavely formed from a periphery of the bobbin (1110) areformed on the four straight sections formed on the periphery of thebobbin (1110). The first driving unit (1120) is oppositely coupled tothe straight sections formed on the periphery of the bobbin (1110). Byway of a non-limiting example, the first driving unit (1120) may bemutually oppositely arranged on two mutually facing straight sectionsamong the four straight sections formed on the periphery of the bobbin(1110) or the four straight sections.

In the exemplary embodiment of the present disclosure, the first drivingunit (1120) may include a magnet, where the magnet may be, by way of anon-limiting example, a two-pole magnet or a four-pole flat magnet. Thestator (1200) includes a second driving unit (1220) and a terminal plate(1230).

Now, referring to FIGS. 7, 8 and 9, the housing (1210) takes a shape ofa square cylinder opened at a bottom. The housing (1210) may be formedby injection-molding process using synthetic resin, for example. Thehousing (1210) is arranged therein with the rotor (1100) and wraps thefirst driving unit (1120) arranged at the periphery of the rotor (1100).

In an exemplary embodiment of the present disclosure, the housing (1210)takes a shape of a square cylinder including an upper plate (1212)formed with an interference prevention unit (1211) and lateral walls(1214). The upper plate (1212) of the housing (1210) takes a shape of asquare plate, when viewed from a top plan, and the upper plate (121) iscentrally formed with an opening exposing a lens (1130). The lateralwalls (1214) of the housing (1210) are extended to a direction wrappingthe rotor (1110) from an edge of the upper plate (1212) of the housing(1210), and each of the lateral walls takes a shape of a plate.

The second driving unit (1220) of the stator (1200) is formed by windinga long wire coated with an insulation resin. In an exemplary embodimentof the present disclosure, the second driving unit (1220) includes acoil block wound in a shape of a square frame. In an exemplaryembodiment of the present disclosure, four second driving units (1220)may be formed on the housing (1210, described later) for performing ahandshake compensation function, each unit spaced apart at an equaldistance.

One lateral end and the other lateral end facing the one lateral end ofthe second driving unit (1220) may be mutually oppositely formedrelative to the second driving unit (1220). For way of a non-limitingexample, the one lateral end of the second driving unit (1220) may bearranged at a left side of the second driving unit (1220), and the otherlateral end of the second driving unit (1220) may be arranged at a rightside of the second driving unit (1220).

The second driving unit (1220) has a predetermined thickness because ofbeing formed with the long wire insulated by an insulation resin, and ina case the second driving unit (1220) having the predetermined thicknessis arranged on the lateral wall (1214) of the housing (1210), the VCM(1800) may increase in terms of volume.

In an exemplary embodiment of the present disclosure, a partcorresponding to the first driving unit (1120) of the rotor (1110) on aperipheral surface of the lateral wall (1214) of the housing (1210) isformed with an accommodation groove (not shown) in order to inhibit theVCM (1800) from increasing in terms of volume resultant from the seconddriving unit (1220). The accommodation groove formed on the peripheralsurface of the lateral wall (1214) at the housing (1210) takes a shapecorresponding to that of the second driving unit (1220). Depth of theaccommodation groove is preferably formed greater than that of thesecond driving unit (1220) in order to inhibit the second driving unit(1220) from protruding from a periphery of the lateral wall (1214) ofthe housing (1210).

Although the exemplary embodiment of the present disclosure hasexplained and illustrated that an accommodation groove of groove shapeis formed at the periphery of the lateral wall (1214) of the housing(1210), alternatively, the housing (1210) corresponding to the firstdriving unit (1120) may be formed with a through hole accommodating thesecond driving unit (1220)

Meanwhile, in a case the housing (1210) is arranged with the seconddriving unit (1220) corresponding to each of the first driving unit(1120), it is difficult to provide a driving signal to the seconddriving unit (1220). Particularly, in a case the housing (1210) ismanufactured with a synthetic resin, it is more difficult to transmit adriving signal to the second driving unit (1220) from a PCB (PrintedCircuit Board) arranged at a rear surface of the base (1300, describedlater).

The terminal plate (1230) serves to transmit to the second driving unit(1220) a driving signal provided from the PCB arranged at the rearsurface of the base (1300). The terminal plate (1230) is manufactured ina form of a metal plate formed with a thin thickness, and a part or anentire part of the terminal plate (1230) contacting the second drivingunit (1220) may be formed with a plated layer (described later) forimproving an electric contact characteristic with the second drivingunit (1220). The terminal plate (1230) is formed in parallel with thelateral wall (1214) of the housing (1210). The terminal plate (1230) isintegrally formed with the housing (1210) by insert injection moldingprocess. A part of the terminal plate (1230) inserted into the housing(1210) is exposed by the accommodation groove accommodating the seconddriving unit (1220).

Although the terminal plate (1230) inserted into the housing (1210) isexplained and illustrated in the exemplary embodiment of the presentdisclosure, alternatively the terminal plate (1230) may be assembled bybeing inserted into an insertion groove formed at the housing (1210).

In the exemplary embodiment of the present disclosure, a distal end ofthe terminal plate (1230) is protruded at a predetermined length from abottom surface of the housing (1210) to pass through the base (1300).

The terminal plate (1230) exposed by the accommodation groove of thehousing (1210) is respectively contacted by one lateral end (1222) andthe other lateral end (1224) of the second driving unit (1220), and theterminal plate (1230) is electrically connected by the one lateral endand the other lateral end (1222, 1224) of the second driving unit(1220). The terminal plate (1230) and the one lateral end (1222) of thesecond driving unit (1220), and the terminal plate (1230) and the otherlateral end (1224) of the second driving unit (1220) are mutually andelectrically connected by a connection member.

By way of a non-limiting example, the connection member may be a lowmelting point, metal solder electrically connecting the one lateral end(1222) of the second driving unit (1220) and the plate terminal (1230),and the other lateral end (1224) of the second driving unit (1220) andthe terminal plate (1230). At this time, in a case a wire forming thesecond driving unit (1220) includes a copper, it is preferable, asexplained above, that a plated layer be formed at a part on the terminalplate (1230), where the one lateral end (1222) and the other lateral end(1224) of the second driving unit (1220) are connected, because of badconnection characteristic of the plate terminal (1230) and the seconddriving unit (1220). Alternatively, the connection member may include aconductive adhesive having adhesive power and conductivity.

Referring to FIG. 7 again, the base (1300) takes a shape of a cube, andbase (1300) is centrally formed with an opening (1305). The base (1300)is protrusively formed with a coupling pillar (1310) for being coupledwith the housing (1200). The coupling pillar (1310) of the base (1300)and a coupling groove formed at the housing corresponding to thecoupling pillar (1310) are coupled by a press-fitting method. The base(1300) is mounted at a rear surface with an IR (Infrared) filter and animage sensor module.

The case (1400) wraps the stator (1200) wrapping the rotor (1100), andinhibits electromagnetic wave generated from the second driving unit(1220) of the stator (1200) or electromagnetic wave coming from outsidefrom being applied to the second driving unit (1220). The case (1400)may be formed by press work of a metal plate for interrupting theelectromagnetic wave. The case (1400) includes an upper plate (1410) anda lateral plate (1420).

The upper plate (1410) and the lateral plate (1420) are integrallyformed. The upper plate (1410), when viewed from a top plan, takes ashape of a square plate, and the upper plate (1410) is centrally formedwith an opening (1405) exposing a lens (1130). An area (plane) of theopening (1405) at the upper plate (1410) is formed greater than that ofthe bobbin (1110) to allow the bobbin (1110) mounted with the lens(1130) to get in or get out of the opening of the upper plate (1410).

The lateral plate (1420) is extended from an edge of the upper plate(1410) along a periphery of the lateral wall (1214) of the housing(1210) at the stator (1200), and the lateral plate (1420) is fixed tothe base (1300).

An elastic member (1250) is coupled to an upper end of the rotor (1100)to elastically support the rotor (1100), and the elastic member (1250)elastically supports the rotor (1100) to allow the rotor (1100) to floatfrom the base (1300) in a case no driving signal is applied to the rotor(1100) and/or the stator (1200). The rotor (1100) is bi-directionallydriven relative to the base (1300) to perform the auto focusing orhandshake compensation functions while the elastic member (1250) allowsthe rotor (1100) to float from an upper surface of the base (1300). Theelastic member (1250) includes an inner elastic unit (1252), an outerelastic unit (1254) and an elastic connection unit (1256).

The inner elastic unit (1252) is coupled to a coupling lug (1112) formedat an upper surface of the bobbin (1110), and the inner elastic unit(1252) may be shaped of a round ring, for example.

The outer elastic unit (1254) is arranged outside of the inner elasticunit (1252), and the outer elastic unit (1254) takes a shape of a strip,for example, and is arranged on an upper plate (1212) of the housing(1210).

The elastic connection unit (1256) connects the outer elastic unit(1254) and the inner elastic unit (1252) to provide elasticity to theinner elastic unit (1252). The elastic connection unit (1256) takes ashape of a long strip generating elasticity by being bent in a zigzagstyle.

Meanwhile, an additional elastic member (1270) takes a shape similar tothat of the elastic member (1250), and the additional elastic member(1270) is coupled to a bottom surface of the bobbin (1110) toelastically support the bobbin (1110).

The VCM (1800) according to an exemplary embodiment of the presentdisclosure is such that, in a case no driving signal is applied to thefirst and second driving units (1120, 1220), the rotor (1100) isdistanced from the upper surface of the base by the elastic member(1250) to maintain a floated state.

The rotor (1100) floated by being distanced from the upper surface ofthe base (1300) in a case no driving signal is applied to the first andsecond driving units (1120, 1220) is driven to a direction distancingfrom the upper surface of the base (1300) or to a direction nearing tothe upper surface of the base (1300) in response to the driving signalapplied to the first and second driving units (1120, 1220).

Particularly, in a case the rotor (1100) is driven to a directionnearing to the upper surface of the base (1300) in response to thedriving signal applied to the first and second driving units (1120,1220), the elastic connection unit (1256) of the elastic member (1250)arranged at the upper surface (1212) of the housing (1210) at the stator(1200) and the inner elastic unit (1252) also move downwardly along withthe rotor (1100), where the elastic connection unit (1256) is broughtinto contact with the upper plate (1212) of the housing (1210) bydisplacement of the elastic connection unit (1256) of the elastic member(1250), whereby the rotor (1100) is inhibited from being normallydriven.

Although the driving fault of the rotor (1100) is not generated on aunidirectional driving VCM driven to one direction distancing from theupper surface of the base, the rotor (1100) may be driven to a directionnearing to the upper surface of the base (1300) in a bi-directionallydriven VCM according to the exemplary embodiment of the presentdisclosure.

Hence, as illustrated in FIGS. 7 to 9, an interference prevention unit(1211) is formed, according to an exemplary embodiment of the presentdisclosure, on the upper plate (1212) of the housing (1210) in order toinhibit an interference of the upper plate (1212) of the housing (1210)and the elastic connection unit (1256) of the elastic member (1250)causing a driving fault of the rotor (1100) generated by bidirectionaldriving of the rotor (1100). The interference prevention unit (1211)formed on the upper plate (1212) of the housing (1210) is formed on theupper plate (1212) of the housing (1210) is formed in a shape of aconcave recess about an opening exposing the lens (1130).

The interference prevention unit (1211) according to an exemplaryembodiment of the present disclosure may be selectively formed at aposition corresponding to that of the elastic connection unit (1256) ofthe elastic member (1250) at the upper plate (1212) of the housing(1210).

Referring to FIG. 9, a floor surface of the interference prevention unit(1211) concavely formed on the upper plate (1212) of the housing (1210)may be formed in parallel with the upper plate (1212) of the housing(1210). Alternatively, the interference prevention unit (1211) accordingto an exemplary embodiment of the present disclosure may be continuouslyformed along an ambience of the opening formed on the upper plate (1212)of the housing (1210).

FIG. 10 is a cross-sectional view illustrating an interferenceprevention unit of a housing according to an exemplary embodiment of thepresent invention.

Referring to FIG. 10, an interference prevention unit (1211 a) formed onan upper plate (1212) of a housing (1210) and formed in a shape of aconcave recess about an opening exposing a lens (1130) is formeddownwardly and slantly formed relative to the upper plate (1212) of thehousing (1210) in response to movement of an elastic connection unit(1256) of an elastic member (1250).

Although the exemplary embodiment of the present disclosure hasillustrated and explained the interference prevention unit (1211) isformed on an upper plate (1212) of a housing (1210) and formed in ashape of a concave recess about an opening exposing a lens (1130), theinterference prevention unit (1211) may be formed with an opening forpassing a part corresponding to the elastic connection unit (1256) ofthe elastic member (1250) on the upper plate (1212) of the housing(1210).

Furthermore, in a case the interference prevention unit (1211) is anopening for passing a part corresponding to the elastic connection unit(1256) of the elastic member (1250) on the upper plate (1212) of thehousing (1210), an opening area of the interference prevention unit(1211) may be formed greater than an area of the elastic connection unit(1256) at the elastic member (1250).

Now, operation of the rotor (1100) in the VCM (1800) will be describedwith reference to FIGS. 11, 12 and 13. In a case no driving signal isapplied to the first and second driving units (1120, 1220), a floatedstate of the rotor (1100) is maintained by the elastic member (1250)relative to the upper surface of the base (1300) as illustrated in FIG.13.

In a case the driving signal is applied to the first and second drivingunits (1120, 1220) to allow the rotor (1100) to be distanced from theupper surface of the base (1300) as illustrated in FIG. 12, the innerelastic unit (1252) and the elastic connection unit (1256) at theelastic member (1250) ascend along with the rotor (1100) to inhibit theelastic member (1250) from generating interference.

Meanwhile, In a case the driving signal is applied to the first andsecond driving units (1120, 1220) to allow the rotor (1100) to be drivento a direction nearing to the upper surface of the base (1300) asillustrated in FIG. 8, the inner elastic unit (1252) and the elasticconnection unit (1256) at the elastic member (1250) may descend alongwith the rotor (1100) to allow the elastic connection unit (1256) of theelastic member (1250) to be brought into contact with the upper plate(1212) of the housing (1210). However, in the exemplary embodiment ofthe present disclosure, the interference prevention unit (1211)inhibiting the upper plate (1212) of the housing (1210) from contactingthe elastic connection unit (1256) is formed on the upper plate (1212)of the housing (1210) to inhibit the elastic connection unit (1256) ofthe elastic member (1250) from mutually contacting the housing (1210).

As apparent from the foregoing detailed description, the rotor maintainsa state of being distanced from the base in case of no driving signal,the rotor is bi-directionally driven to a direction distancing from thebase or to a direction facing the base in response to the application ofthe driving signal, and particularly, the elastic member coupled to therotor is inhibited from generating a mutual interference with the upperplate of the housing fixing the second driving unit in a case the rotoris driven to a direction facing the base, whereby the VCM is inhibitedfrom generating a driving fault during the focusing operation.

Third Exemplary Embodiment

Hereinafter, a third exemplary embodiment of the present disclosure willbe described, where different reference numerals will be provided to thesame configuration as that of the first and second exemplary embodimentsof the present disclosure in order to distinguish the third exemplaryembodiment from the first and second exemplary embodiments.

FIG. 14 is an exploded perspective view illustrating the VCM of FIG. 6.

Referring to FIG. 14, a VCM (2800) includes a rotor (2100), a stator(2200), a base (2300), a case (2400), an elastic member (2540), aninterference prevention unit (2600) and a cover member (2700).

The rotor (2100) includes a bobbin (2110) and a first driving unit(2120). The rotor (2100) vertically moves on the base in response tointeraction with the stator (2200, described later) to perform the autofocusing function and to perform a handshake compensation function bytilting on the base (2300). The bobbin takes a shape of a cylinder, forexample, and the bobbin (2110) is formed at an inner circumferentialsurface with a female screw unit for being coupled to a lens (2130). Thebobbin (2110) is formed with a coupling lug (2112) for being coupled tothe elastic member (2540, described later). A periphery of the bobbin(2110) is alternately formed with a curve section and a straightsection. The bobbin (2110) is formed at the outer periphery with four(4) straight sections and four (4) curved sections.

Grooves concavely formed from the periphery of the bobbin (2110) areformed on the four straight sections formed on the periphery of thebobbin (2110). The first driving unit (2120) is oppositely coupled tothe straight sections formed on the periphery of the bobbin (2110). Byway of a non-limiting example, the first driving unit (2120) may bemutually oppositely arranged on two mutually facing straight sectionsamong the four straight sections formed on the periphery of the bobbin(2110) or on the four straight sections.

In the exemplary embodiment of the present disclosure, the first drivingunit (2120) may include a magnet, where the magnet may be, by way of anon-limiting example, a two-pole magnet or a four-pole flat magnet. Thestator (2200) includes a housing (2210), a second driving unit (220) anda terminal plate (2230).

The housing (2210) takes a shape of a square cylinder opened at an uppersurface and a bottom surface. The housing (2210) is arranged thereinwith the rotor (2200), and the housing (2210) wraps a first driving unit(2120) arranged at the periphery of the bobbin (2110) of the rotor(2100).

In an exemplary embodiment of the present disclosure, the housing (2210)takes a shape of a square cylinder including four lateral walls (2212).The housing (2210) may be formed by injection molding process usingsynthetic resin, for example.

The second driving unit (2220) is formed by winding a long wire coatedwith an insulation resin. In an exemplary embodiment of the presentdisclosure, the second driving unit (2220) includes a coil block woundin a shape of a square frame. In an exemplary embodiment of the presentdisclosure, four second driving units (2220) may be formed on thehousing (2210, described later) for performing a handshake compensationfunction, each unit spaced apart at an equal distance.

One lateral end and the other lateral end facing the one lateral end ofthe second driving unit (2220) may be mutually oppositely formedrelative to the second driving unit (2220). By way of a non-limitingexample, the one lateral end of the second driving unit (2220) may bearranged at a left side of the second driving unit (2220), and the otherlateral end of the second driving unit (2220) may be arranged at a rightside of the second driving unit (2220).

The second driving unit (2220) has a predetermined thickness because ofbeing formed with the long wire insulated by an insulation resin, and ina case the second driving unit (2220) having the predetermined thicknessis arranged on the lateral wall (2212) of the housing (2210), a VCM(2800) may increase in terms of volume.

In an exemplary embodiment of the present disclosure, a partcorresponding to the first driving unit (2120) of the rotor (2110) on aperipheral surface of the lateral wall (2212) of the housing (2210) isformed with an accommodation groove (2214) in order to inhibit the VCM(2800) from increasing in terms of volume resultant from the seconddriving unit (2220). The accommodation groove (2214) formed on theperipheral surface of the lateral wall (2212) at the housing (2210)takes a shape corresponding to that of the second driving unit (2220).Depth of the accommodation groove (2214) is preferably formed greaterthan that of the second driving unit (2220) in order to inhibit thesecond driving unit (2220) from protruding from a periphery of thelateral wall (2212) of the housing (2210).

Although the exemplary embodiment of the present disclosure hasexplained and illustrated that an accommodation groove (2214) of grooveshape is formed at the periphery of the lateral wall (2212) of thehousing (2210), alternatively, the housing (2210) corresponding to thefirst driving unit (2120) may be formed with a through holeaccommodating the second driving unit (2220).

Meanwhile, in a case the housing (2210) is arranged with the seconddriving unit (2220) corresponding to each of the first driving unit(2120), it is difficult to provide a driving signal to the seconddriving unit (2220). Particularly, in a case the housing (2210) ismanufactured with a synthetic resin, it is more difficult to transmit adriving signal to the second driving unit (2220) from a PCB (PrintedCircuit Board) arranged at a rear surface of the base (2300, describedlater).

The terminal plate (2230) serves to transmit to the second driving unit(2220) a driving signal provided from the PCB arranged at the rearsurface of the base (2300). The terminal plate (2230) is manufactured ina form of a metal plate formed with a thin thickness, and a part or anentire part of the terminal plate (2230) contacting the second drivingunit (2220) may be formed with a plated layer (described later) forimproving an electric contact characteristic with the second drivingunit (2220). The terminal plate (2230) is formed in parallel with thelateral wall (2212) of the housing (2210). The terminal plate (2230) isintegrally formed with the housing (2210) by insert injection moldingprocess. A part of the terminal plate (2230) inserted into the housing(2210) is exposed by the accommodation groove (2214) accommodating thesecond driving unit (2220).

Although the terminal plate (2230) inserted into the housing (2210) isexplained and illustrated in the exemplary embodiment of the presentdisclosure, alternatively the terminal plate (2230) may be assembled bybeing inserted into an insertion groove formed at the housing (2210).

In the exemplary embodiment of the present disclosure, a distal end ofthe terminal plate (2230) is protruded at a predetermined length from abottom surface of the housing (2210) to pass through the base (2300).

The terminal plate (2230) exposed by the accommodation groove (2214) ofthe housing (2210) is respectively contacted by one lateral end (2222)and the other lateral end (2224) of the second driving unit (2220), andthe terminal plate (2230) is electrically connected by the one lateralend and the other lateral end (2222, 2224) of the second driving unit(2220). The terminal plate (2230) and the one lateral end (2222) of thesecond driving unit (2220), and the terminal plate (2230) and the otherlateral end (2224) of the second driving unit (2220) are mutually andelectrically connected by a connection member.

By way of a non-limiting example, the connection member may be a lowmelting point, metal solder electrically connecting the one lateral end(2222) of the second driving unit (2220) and the plate terminal (2230),and the other lateral end (2224) of the second driving unit (2220) andthe terminal plate (2230). At this time, in a case a wire forming thesecond driving unit (2220) includes a copper, it is preferable, asexplained above, that the plated layer be formed at a part on theterminal plate (2230) where the one lateral end (2222) and the otherlateral end (2224) of the second driving unit (2220) are connected,because of bad connection characteristic of the plate terminal (2230)and the second driving unit (1220). Alternatively, the connection membermay include a conductive adhesive having adhesive power andconductivity.

Referring to FIG. 14 again, the base (2300) takes a shape of a cube, andbase (2300) is centrally formed with an opening (2305). The base (2300)is protrusively formed with a coupling pillar (2310) for being coupledwith the housing (2200). The coupling pillar (2310) of the base (2300)and a coupling groove formed at the housing (2200) corresponding to thecoupling pillar (2310) are coupled by a press-fitting method. The base(2300) is mounted at a rear surface with an IR (Infrared) filter and animage sensor module.

The case (2400) wraps the stator (2200) wrapping the rotor (2100), andinhibits electromagnetic wave generated from the second driving unit(2220) of the stator (2200) or electromagnetic wave coming from outsidefrom being applied to the second driving unit (2220). The case (2400)may be formed by press work of a metal plate for interrupting theelectromagnetic wave. The case (1400) includes an upper plate (410) anda lateral plate (2420). The upper plate (2410) and the lateral plate(2420) are integrally formed.

The upper plate (2410), when viewed from a top plan, takes a shape of asquare plate, and the upper plate (2410) is centrally formed with anopening (2405) exposing a lens (2130). An area (plane) of the opening(2405) at the upper plate (2410) is formed greater than that of thebobbin (2110) to allow the bobbin (2110) mounted with the lens (2130) toget in or get out of the opening of the upper plate (2410).

The lateral plate (2420) is extended from an edge of the upper plate(2410) along a periphery of the lateral wall (2212) of the housing(2210) at the stator (2200), and the lateral plate (2420) is fixed tothe base (2300).

Referring to FIGS. 14, 15 and 15, an elastic member (2540) is coupled tothe rotor (2100) to elastically support the rotor (2100), and theelastic member (2540) elastically supports the rotor (2100) to allow therotor (2100) to float from the base (2300) in a case no driving signalis applied to the rotor (2100) and/or to the stator (2200). The rotor(2100) is bi-directionally driven relative to the base (2300) to performthe auto focusing function by causing the elastic member (2540) to allowthe rotor (2100) to float from the base (2300). The elastic member(2540) includes an inner elastic unit (2510), an outer elastic unit(2520 and an elastic connection unit (2530).

The inner elastic unit (2510) is coupled to a coupling lug (2112) formedat the bobbin (2110), and the inner elastic unit (2510) may be shaped ofa round ring, for example.

The outer elastic unit (2520) is arranged outside of the inner elasticunit (2510), and the outer elastic unit (2520) takes a shape of a strip.

The elastic connection unit (2530) connects the inner elastic unit(2510) and the outer elastic unit (2520) to provide elasticity to theinner elastic unit (2510). The elastic connection unit (2530) takes ashape of a long strip generating elasticity by being bent in a zigzagstyle. The elastic member (2540) including the inner elastic unit(2510), the outer elastic unit (2520) and the elastic connection unit(2530) is not arranged inside an upper plate (2410) of the case (2400)but on the upper plate (2410).

An additional elastic member (2580) takes a shape similar to that of theelastic member (2540), and the additional elastic member (2580) iscoupled to a bottom surface of the bobbin (2110) to elastically supportthe bobbin (2110).

An interference prevention unit (2600) is interposed between the upperplate (2410) of the case (2400) and the elastic member (2540). Theinterference prevention unit (2600) is driven to a direction where thebobbin (2110) coupled to the inner elastic unit (2510) of the elasticmember (2540) gets closer to the base (2300), and inhibits generation ofa focus operation fault of the bobbin (2110) caused by interferencebetween the elastic connection unit (2530) and the upper plate (2410)arranged underneath the elastic connection unit (2530) duringperformance of focusing operation.

By way of non-limiting example, in a case the interference preventionunit (2600) is not formed between the elastic member (2540) and theupper plate (2410) of the case (2400), the upper plate (2410) should notcontact the elastic connection unit (2530) of the elastic member (2540),where an area of an opening (2405) of the upper plate (2410) must befurther increased to realize the non-contact without the interferenceprevention unit (2600).

In a case the area of the opening (2405) of the upper plate (2410) isfurther increased, foreign objects may enter the VCM (2800) through theopening (2405) to be collected at an inside of the VCM (2800), whereby adefect development rate of the VCM (2800) increases to shorten the lifeof the VCM (2800). In order to inhibit the increased defect developmentrate from increasing, an interference prevention unit (2600) isinterposed between the elastic member (2540) and the upper plate (2410)of the case (2400).

The interference prevention unit (2600) is formed in a shape of a steelplate formed therein with an opening (2605), and the interferenceprevention unit (2600) may be formed by a punching process of a metalplate or an injection molding process of synthetic resin.

Thickness of the interference prevention unit (2600) is so formed as toinhibit the elastic connection unit (2530) of the elastic member (2540)vertically moving along a stroke length of the bobbin (2110) of therotor (2100) from contacting the upper plate (2410). The interferenceprevention unit (2600) formed on the upper plate (2410) of the case(2400) is fixed to the upper plate (2410) by various methods including aspot welding, a laser welding or a soldering. Meanwhile, in a case theinterference prevention unit (2600) is an injection molded body ofsynthetic resin, the interference prevention unit (2600) is fixed to theupper surface of the upper plate (2410) using an adhesive.

In order to allow the interference prevention unit (2600) to beprecisely arranged on a designated position, the interference preventionunit (2600) is formed with a guide hole (2610) for aligning theposition. Meanwhile, a guide lug coupled to the guide hole (2610) of theinterference prevention unit (2600) may be formed on the upper plate(2410) corresponding to the guide hole (2610). An area of the opening(2605) at the interference prevention unit (2600) is formed greater thanthat of the opening (2405) of the upper plate (2410) of the case (2400).

Hence, a part of the upper plate (2410) of the case (2400) is exposedinstead of being covered by the interference prevention unit (2600) in acase the interference prevention unit (2600) is coupled to thedesignated position of the upper plate (2410), where the exposed part isa part corresponding to the elastic connection unit (2530) of theelastic member (2540).

That is, in a case the interference prevention unit (2600) is arrangedon the upper plate (2410), and the outer elastic unit (2520) of theelastic member (2540) is arranged on an upper surface of theinterference prevention unit (2600), a gap corresponding to a thicknessof the interference prevention unit (2600) is formed between the elasticconnection unit (2530) of the elastic member (2540) and the upper plate(2410).

In a case the gap (G) is formed between the elastic connection unit(2530) of the elastic member (2540) and the upper plate (2410) by theinterference prevention unit (2600) as illustrated in FIG. 17, aninterference caused by contact between the elastic connection unit(2530) of the elastic member (2540) and the upper plate (2410) can beinhibited even if the bobbin (2110) is driven to a direction approachingthe base (2300) as in FIG. 19.

Referring to FIGS. 7, 17 and 19, in a case a driving signal raising therotor (2100) is applied to the stator (2200), the bobbin (2110) of therotor (2100) ascends as illustrated in FIG. 18, and the inner elasticunit (2510) and the elastic connection unit (2530) of the elastic member(2540) move upwards. Conversely, in a case a driving signal descendingthe rotor (2100) is applied to the stator (2200), the bobbin (2110) ofthe rotor (2100) descends as illustrated in FIG. 19, and the innerelastic unit (2510) and the elastic connection unit (2530) of theelastic member (2540) move downwards.

The elastic connection unit (2530) of the elastic member (2540) movedownwards along with the rotor (2100) in response to the descent of therotor (2100), whereby the elastic connection unit (2530) is notcontacted to or interfered with the upper plate (2410) by the thicknessof the interference prevention unit (2600).

The cover member (2700) includes an opening exposing the lens (2130),and the cover member (2700) fixes the elastic member (2540) by pressingthe elastic member (2540) arranged on the case (2400).

As apparent from the foregoing detailed description, the rotor maintainsa state of being distanced from the base in case of no driving signalbeing applied, the rotor is bi-directionally driven to a directiondistancing from the base or to a direction facing the base in responseto the application of the driving signal, and particularly, the elasticmember coupled to the rotor and the case covering the rotor areinhibited from generating a mutual interference in a case the rotor isdriven to a direction facing the base, whereby the VCM is inhibited fromgenerating a driving fault during the focusing operation.

The previous description of the present invention is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to the invention will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother variations without departing from the spirit or scope of theinvention. Thus, the invention is not intended to limit the examplesdescribed herein, but is to be accorded the widest scope consistent withthe principles and novel features disclosed herein.

What is claimed is:
 1. A VCM (Voice Coil Motor), the VCM comprising: acase comprising an upper plate and a lateral plate extending from theupper plate; a bobbin disposed in the case; a coil disposed in the case;a magnet disposed in the case and facing the coil; a housing disposedunder the upper plate of the case; a base disposed under the housing andcoupled with the lateral plate of the case; and an upper elastic membercoupled with the bobbin and the housing, and comprising an inner elasticunit coupled to the bobbin, an outer elastic unit coupled to an uppersurface of the housing, and an elastic connection unit connecting theinner elastic unit and the outer elastic unit, wherein the bobbin isspaced apart from both the base and the case at an initial position whenno current is applied to the coil, wherein a first gap between thebobbin and the base is shorter than a second gap between the bobbin andthe upper plate of the case at the initial position, and wherein thehousing comprises a recess formed on the upper surface of the housingand disposed at a position corresponding to that of the elasticconnection unit of the upper elastic member.
 2. The VCM of claim 1,wherein the bobbin is configured to be moved from the initial positionin a first direction approaching the base when a backward current isapplied to the coil and to be moved from the initial position in asecond direction approaching the upper plate of the case when a forwardcurrent is applied to the coil, and wherein a first stroke length of thebobbin in the first direction is shorter than a second stroke length ofthe bobbin in the second direction.
 3. The VCM of claim 2, wherein thebase is in a position facing a ground at an UP posture of the bobbin,the base is in a position perpendicular to the ground at a SIDE postureof the bobbin, and the case is in a position facing the ground at a DOWNposture of the bobbin, and wherein the bobbin is spaced apart from thebase at the DOWN posture in the initial position.
 4. The VCM of claim 3,wherein the bobbin contacts the base at the UP posture in an initialposition and the bobbin contacts the base at the SIDE posture in theinitial position.
 5. The VCM of claim 3, wherein the bobbin moves in thesecond direction after moving in the first direction to perform a focusfunction at the DOWN posture.
 6. The VCM of claim 1, wherein the recessof the housing forms a space in which the elastic connection unit isdisposed when the inner elastic unit is moved to a position lower thanthat of the outer elastic unit.
 7. The VCM of claim 1, wherein thehousing comprises a protrusion protruding from the upper surface of thehousing, wherein the outer elastic unit of the upper elastic membercomprises a hole, and wherein the protrusion of the housing passesthrough the hole of the outer elastic unit of the upper elastic member.8. The VCM of claim 7, wherein the upper plate of the case and the uppersurface of the housing are spaced apart from each other by theprotrusion of the housing.
 9. The VCM of claim 1, wherein the upperplate of the case functions as an upper stopper of the bobbin, andwherein the base functions as a lower stopper of the bobbin.
 10. The VCMof claim 9, wherein the bobbin is overlapped with the base and the upperplate of the case in a direction of an optical axis.
 11. The VCM ofclaim 1, wherein the recess of the housing comprises a slanted surfaceslantly formed relative to the upper surface of the housing.
 12. The VCMof claim 11, wherein the slanted surface of the recess is formed inresponse to movement of the elastic connection unit of the upper elasticmember.
 13. The VCM of claim 3, wherein the bobbin is not driven when acurrent lower than a reference level is applied to the coil and thebobbin is driven when a current higher than the reference level isapplied to the coil at the UP posture.
 14. The VCM of claim 3, whereinthe bobbin is spaced apart from the base because of droop caused by aself-weight of the bobbin to a gravitational direction at the DOWNposture.
 15. The VCM of claim 1, comprising: a lower elastic membercoupled to a lower surface of the bobbin.
 16. A camera module, thecamera module comprising: a PCB (Printed Circuit Board); an image sensordisposed on the PCB; the voice coil motor of claim 1 disposed on thePCB; and a lens coupled with the bobbin of the voice coil motor.
 17. Amobile phone, the mobile phone comprising the camera module of claim 16.18. A VCM (Voice Coil Motor), the VCM comprising: a case comprising anupper plate and a lateral plate extending from the upper plate; a bobbindisposed in the case; a first driving unit disposed on the bobbin; asecond driving unit facing the coil and disposed between the firstdriving unit and the upper plate of the case; a housing disposed betweenthe second driving unit and the upper plate of the case; a base disposedunder the housing and coupled with the lateral plate of the case; and anupper elastic member coupled with the bobbin and the housing, andcomprising an inner elastic unit coupled to the bobbin, an outer elasticunit coupled to an upper surface of the housing, and an elasticconnection unit connecting the inner elastic unit and the outer elasticunit, wherein the bobbin is spaced apart from both the base and the caseat an initial position when no current is applied to the coil, whereinthe bobbin is configured to be moved from the initial position in afirst direction approaching the base when a backward current is appliedto the coil and to be moved from the initial position in a seconddirection approaching the upper plate of the case when a forward currentis applied to the coil, wherein a first stroke length of the bobbin inthe first direction is shorter than a second stroke length of the bobbinin the second direction, and wherein the housing comprises a recessformed on the upper surface of the housing and disposed at a positioncorresponding to that of the elastic connection unit of the upperelastic member.
 19. The VCM of claim 18, wherein the base is in aposition facing a ground at an UP posture of the bobbin, the base is ina position perpendicular to the ground at a SIDE posture of the bobbin,and the case is in a position facing the ground at a DOWN posture of thebobbin, and wherein the bobbin is spaced apart from the base at the DOWNposture in the initial position.
 20. The VCM of claim 18, wherein thefirst driving unit comprises a coil and the second driving unitcomprises a magnet.
 21. A VCM (Voice Coil Motor), the VCM comprising: acase comprising an upper plate and a lateral plate extending from theupper plate; a bobbin disposed in the case; a coil disposed in the case;a magnet disposed in the case and facing the coil; a housing disposedunder the upper plate of the case; a base disposed under the housing andcoupled with the lateral plate of the case; and an elastic membercoupled with the bobbin and the housing, wherein the bobbin is spacedapart from both the base and the case at an initial position when nocurrent is applied to the coil, and wherein a first gap between thebobbin and the base is shorter than a second gap between the bobbin andthe upper plate of the case at the initial position.